A quark model calculation of γ[Formula Presented]ππ including final-state interactions

Publication

Publication

A quark model calculation of the processes [Formula Presented] and [Formula Presented] is performed. At tree level, only charged pions couple to the initial state photons and neutral pions are not expected in the final state. However, a small but significant [Formula Presented] cross section is observed. We demonstrate that this may be accounted for by a rotation in isospin space induced by final-state interactions. The resulting [Formula Presented] cross section is in good agreement with experiment, while the [Formula Presented] cross section is in qualitative agreement with the data.